JP3445453B2 - Molten carbonate fuel cell - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten carbonate fuel cell and a method for producing a molten carbonate fuel cell electrolyte plate holding material, and in particular, it is sandwiched between a pair of conductive electrodes. The present invention relates to a molten carbonate fuel cell having an improved electrolyte plate and a method for producing a holding material used for the electrolyte plate.

[0002]

2. Description of the Related Art The basic structure of a molten carbonate fuel cell is shown in FIG.
Shown in. An electrolyte plate 3 holding an electrolyte made of an alkali carbonate is sandwiched between an anode 1 and a cathode 2 which are a pair of electrodes having conductivity. With the electrolyte plate 3 melted at a high temperature, the housing 4 is attached to the anode 1.
Fuel gas (H ₂ , CO ₂ ) is supplied to the cathode 2 through the supply port 6 and oxidant gas (air, CO ₂ ) is supplied to the cathode 2 through the supply port 8 of the housing 4b. When the fuel gas and the oxidant gas are supplied as described above, the reaction of the following formula (1) occurs at the anode 1 and the reaction of the following formula (2) occurs at the cathode 2 to operate the fuel cell.

H ₂ + CO ₃ ^2- → H ₂ O + CO ₂ + 2e ⁻ (1) 1 / 2O ₂ + CO ₂ + 2e ⁻ → CO ₃ ²⁻ (2) The electrolyte plate used for the molten carbonate fuel cell is Basically, an electrolyte composed of mixed alkali carbonates, and a porous material composed of a holding material for preventing the outflow of the electrolyte that becomes a liquid during high-temperature operation and a reinforcing material for preventing the occurrence of cracks during temperature rise. It is composed by. The mixed alkali carbonate includes Li ₂ CO ₃ , K ₂ CO ₃ and Na ₂
It is used in the form of a mixed salt of two or _three of the three CO ₃ . The holding material has a particle size of 0.05 to 2.
A fine powder of 0 μm γ-lithium aluminate is used. The reinforcing material has a particle size of 10 to 100 μm.
Lithium aluminate is used.

The electrolyte plate is made of carbonate ions (CO ₃ ^2- ).
Not only as a transfer medium, but also as a gas permeation barrier layer for preventing direct reaction gas mixture (gas crossover) between the anode and the cathode. In order to perform such a function, it is necessary that the electrolyte is sufficiently retained in the electrolyte plate. The outflow of electrolyte (electrolyte loss) not only causes an increase in internal resistance, but also causes gas crossover.

The electrolyte plate having such a function has heretofore been formed by forming a porous body having an appropriate fine structure from the holding material and the reinforcing material, and then impregnating the porous body with an electrolyte composed of a mixed alkali carbonate. It is manufactured by the matrix method.

However, when the fuel cell is operated for a long time, the holding material γ-lithium aluminate is α
-Phase change to lithium aluminate, and the microstructure of the porous body (matrix) changes due to the agglomeration and particle growth of the holding material particles accompanying it. As a result, rough holes are formed in the electrolyte plate, which causes electrolyte loss, resulting in a short life.

From the above, Japanese Patent Laid-Open No. 63-294
Japanese Patent No. 668 discloses a holding material having an average particle diameter of α of 0.1 μm.
-A method of using lithium aluminate based on lithium aluminate is disclosed. However, α-
Even with an electrolyte plate using a holding material containing lithium aluminate as a main component, the holding material particles still aggregate and grow, which causes the structural change of the matrix.

In the above-mentioned conventional molten carbonate fuel cell, the fine structure of the porous body changes due to the agglomeration and grain growth of the retaining material particles in the porous body of the electrolyte plate, resulting in electrolyte loss. There was a problem that excellent life characteristics could not be obtained.

On the other hand, JP-A-2-243511 discloses a method of obtaining a low specific surface area α-lithium aluminate by reacting γ-lithium aluminate having a specific surface area of 20 m ² / g in a molten state. . However, this method requires a reaction for 5000 hours or more in order to obtain highly pure and highly crystalline α-lithium aluminate, resulting in an increase in cost and is not a practical method.

[0010]

SUMMARY OF THE INVENTION The present invention reduces the outflow of electrolyte from an electrolyte plate, increases the internal resistance associated with the outflow of the electrolyte, and suppresses the occurrence of gas crossover. Type fuel cell.

Another object of the present invention is to provide a method for producing a holding material for a molten carbonate type fuel electrolyte plate, which is less likely to cause grain growth even when the electrolyte plate is used for a long time, at a low cost.

[0012]

A molten carbonate fuel cell according to the present invention is sandwiched between a fuel electrode, an oxidizer electrode, the fuel electrode and the oxidizer electrode, and has a holding material and a reinforcing material. An electrolyte plate in which a porous body containing the electrolyte is impregnated with an electrolyte containing an alkali carbonate, and the holding material has a specific surface area of 20 m.
² / g or more α-lithium aluminate
Grain growth of thium aluminate in molten carbonate
Α-Lithium aluminum obtained by removing salts
Content of 90% by weight or more and in powder X-ray diffraction
The half-value width of the (104) peak of α-LiAlO ₂ is 0.
It is characterized in that it is made of lithium aluminate at 60 ° or less, and the reinforcing material is made of at least one selected from lithium aluminate, alumina and stabilized zirconia.

Such a molten carbonate fuel cell according to the present invention is mainly composed of α-lithium aluminate and has a half width of the (104) peak of α-LiAlO ₂ of 0.60 ° in powder X-ray diffraction. A porous body containing a reinforcing material made of at least one selected from the following holding materials and lithium aluminate, alumina, and stabilized zirconia is provided with an electrolyte plate in which an electrolyte solution containing an alkali carbonate is impregnated. In such a molten carbonate fuel cell, for example, in the operation of 600 ° C. to 700 ° C. and an atmosphere of CO ₂ 10% to 30%, the holding material in the molten carbonate mainly contains α-lithium aluminate, and the powder X-ray is used. Α- in diffraction
Since the full width at half maximum of the (104) peak of LiAlO ₂ has a specific value, it can be stably present in the molten carbonate for a long period of time without causing phase transformation. As a result, the agglomeration and particle growth of the holding material particles in the electrolyte plate can be suppressed, so that the microstructure of the porous plate (matrix) can be prevented from changing. Further, the reinforcing material made of the above-mentioned specific material hardly causes aggregation / aggregation with α-lithium aluminate, which is a holding material, and can improve the stability of the fine structure of the electrolyte plate during operation.

Therefore, the outflow of the electrolyte from the electrolyte plate is reduced to increase the internal resistance due to the outflow of the electrolyte.
Since generation of gas crossover can be suppressed, a long-life molten carbonate fuel cell can be obtained.

In the molten carbonate fuel cell according to the present invention, the holding material preferably contains 90% by weight or more of α-lithium aluminate. In the molten carbonate fuel cell according to the present invention, the holding material is preferably a powder having an average particle diameter of 0.05 to 2.0 μm.

In the molten carbonate fuel cell according to the present invention, the holding material is α-LiAl in powder X-ray diffraction.
The full width at half maximum of the (104) peak of O ₂ is preferably 0.45 ° or less.

In the molten carbonate fuel cell according to the present invention, it is preferable that the reinforcing material is particles of α-lithium aluminate. Another molten carbonate fuel cell according to the present invention is an alkaline carbonate which is sandwiched between a fuel electrode, an oxidizer electrode, and the fuel electrode and the oxidizer electrode, and which has a porous material including a holding material and a reinforcing material. And an electrolyte plate impregnated with an electrolyte containing salt, wherein the holding material has a specific surface area of 20 m ^2.
/ G or more α-lithium aluminate-based lithium
Grain growth of umluminate in molten carbonate
Α-lithium aluminum obtained by removing
Content of 90% by weight or more and in powder X-ray diffraction
The half width of the (104) peak of α-LiAlO ₂ is 0.6.
The reinforcing material is composed of lithium aluminate having a temperature of 0 ° or less, and the reinforcing material is composed of at least one fiber selected from lithium aluminate, alumina, stabilized zirconia, and lithium zirconate.

Such another molten carbonate fuel cell according to the present invention is mainly composed of α-lithium aluminate,
And (10 of α-LiAlO ₂ in powder X-ray diffraction
4) Alkali carbonate is contained in a porous body containing a holding material having a peak half width of 0.60 ° or less and a reinforcing material composed of at least one fiber selected from lithium aluminate, alumina, zirconia and lithium zirconate. It has a structure including an electrolyte plate impregnated with an electrolytic solution. Such a molten carbonate fuel cell has, for example, 600 ° C. to 700 ° C., C
In the operation in the atmosphere of O ₂ 10% to 30%, the holding material in the molten carbonate is mainly α-lithium aluminate,
And (10 of α-LiAlO ₂ in powder X-ray diffraction
4) Since the full width at half maximum of the peak has a specific value, it can be stably present in the molten carbonate for a long period of time without causing phase transformation. As a result, the agglomeration and particle growth of the holding material particles in the electrolyte plate can be suppressed, so that the microstructure of the porous plate (matrix) can be prevented from changing. Further, the reinforcing material made of fibers of the above-mentioned specific material is unlikely to aggregate / aggregate with α-lithium aluminate, which is a holding material, and can enhance the stability of the fine structure of the electrolyte plate during operation.

Therefore, the outflow of the electrolyte from the electrolyte plate is reduced to increase the internal resistance due to the outflow of the electrolyte,
Since generation of gas crossover can be suppressed, a long-life molten carbonate fuel cell can be obtained.

In another molten carbonate fuel cell according to the present invention, the reinforcing material has an average diameter of 0.5 to 5 μm and 50
Short fibers having an average length of not more than μm are preferred. In another molten carbonate fuel cell according to the present invention, it is preferable that the short fibrous reinforcing material comprises at least one selected from β-lithium aluminate and γ-lithium aluminate.

In another molten carbonate fuel cell according to the present invention, the reinforcing material has an average diameter of 1 to 15 μm and 0.1.
It is preferably a long fiber having an average length of ˜3 mm. In another molten carbonate fuel cell according to the present invention, it is preferable that the long fibrous reinforcing material comprises at least one selected from alumina, lithium aluminate and zirconia.

The method for producing a holding material for a molten carbonate type fuel cell electrolyte plate according to the present invention is carried out by heat treating a mixture of aluminum hydroxide powder having a specific surface area of 100 m ² / g or more and a carbonate containing lithium carbonate to obtain lithium aluminum. The step of producing a nate and the produced lithium aluminate at 700 to 8
And a step of removing the carbonate after the grains are grown in the molten carbonate at 00 ° C.

By using aluminum hydroxide having such a high specific surface area as a starting material, lithium aluminate mainly consisting of α-lithium aluminate is produced, and grains are grown in a molten carbonate to obtain crystallinity and It is possible to obtain a holding material having a high degree of purity and containing single particle α-lithium aluminate in a short time. A porous body is formed from the obtained holding material and the above-mentioned reinforcing material, and an electrolyte plate is prepared by impregnating the porous body with an electrolyte containing an alkali carbonate, and incorporating this into a molten carbonate fuel cell. As a result, the aggregation and particle growth of the holding material particles in the electrolyte plate can be suppressed, and the electrolyte loss can be reduced.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a molten carbonate fuel cell according to the present invention will be described in detail below with reference to FIGS. 2 and 3. The molten carbonate fuel cell of the present invention includes an anode (fuel electrode) 11, a cathode (air electrode) 12, and an electrolyte plate 13 which is arranged between the anode 11 and the cathode 12 and holds an electrolyte. These anodes 11,
The cathode 12 and the electrolyte plate 13 are used as a unit cell, and a plurality of unit cells are laminated with the separator 14 interposed therebetween. A pair of opposite edges of the anode 11 arranged on the upper surface of the electrolyte plate 13 are located inside at a desired distance from the edges of the electrolyte plate, and both sides of the electrolyte plate 13 where the anode 11 does not exist. An edge seal plate 15 a is arranged between the edge portion and the separator 14. A pair of edge portions of the cathode 12 disposed on the lower surface of the electrolyte plate 13 orthogonal to the edge seal plate 15a are located inside at a desired distance from the edge portion of the electrolyte plate 13, and the cathode 12 is present. The edge seal plate 15b is provided between both edges of the electrolyte plate 13 and the separator 14.
Are arranged. The anode 11 and the separator 14
In the space defined by the edge seal plate 15a (fuel gas distribution space), a perforated plate 16a having conductivity and a corrugated plate 17a as a current collector plate are sequentially stacked from the anode 11 side. In the space defined by the cathode 12, the separator 14 and the edge seal plate 15b (oxidant gas flow space), a perforated plate 16b having conductivity as a current collector plate and a corrugated plate 17b are sequentially laminated from the cathode side. Has been done. On the four side surfaces of the stack power generation element in which a plurality of such unit cells are stacked with the separator 14 sandwiched therebetween,
Manifolds 19 each having a frame-shaped flange 18 are arranged. Further, frame-shaped manifold seal plates 20 are respectively interposed between the four side surfaces of the stack power generation element and the flange 18 of the manifold 19. A supply pipe 22 for supplying the fuel gas 21 is attached to a manifold (not shown) corresponding to the side surface of the power generation element in which the fuel gas distribution space is exposed. In the manifold 19 on the side opposite to the supply pipe 22,
A gas exhaust pipe 23 is attached. A supply pipe 25 for supplying the oxidant gas 24 is attached to a manifold (not shown) corresponding to the side surface of the power generation element where the oxidant gas flow section is exposed. A gas exhaust pipe 26 is attached to the manifold 19 on the opposite side of the supply pipe 25.

The anode 11 and the cathode 12 are
For example, it is formed from a porous sintered body of nickel or a nickel-based alloy. The separator 14, the edge seals 15a and 15b, the perforated plates 16a and 16b.
The corrugated plates 17a and 17b are made of, for example, stainless steel.

As the fuel gas 21, for example, a mixed gas of hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) can be used. The electrolyte plate 13 has a structure in which a porous body having a porosity of 40 to 65% including a holding material (a) and a reinforcing material (b) is impregnated with an electrolyte (c) containing an alkali carbonate in a molten state. There is. The holding material (a), the reinforcing material (b) and the alkali carbonate (c) will be described in detail below.

Retaining Material (a) This retaining material is mainly composed of α-lithium aluminate,
And (10 of α-LiAlO ₂ in powder X-ray diffraction
4) It is made of a material having a peak half width of 0.60 ° or less.
Here, powder X-ray diffraction is performed using the Cu Kα ₁ ray (wavelength 1.54).
056A).

The holding material mainly composed of α-lithium aluminate preferably contains 90% by weight or more, more preferably 95% by weight or more of α-lithium aluminate. When the proportion of α-lithium aluminate constituting the holding material is less than 90% by weight, the operating conditions of the molten carbonate fuel cell, for example, 600 to 700 ° C., CO ₂ 10
In a 30% atmosphere, the fine structure of the porous body changes due to the aggregation and growth of particles accompanying the phase change of the remaining γ-lithium aluminate into α-lithium aluminate, and coarse pores are likely to occur.

The holding material α-LiAlO ₂ (10
4) The half width of the peak is defined to be 0.60 ° or less.
The reason is as follows. The half width is 0.6
An electrolyte plate obtained by impregnating a porous body having a holding material exceeding 0 ° with an electrolyte containing an alkali carbonate is an α-lithium aluminate present in a molten salt during operation of a fuel cell incorporating the electrolyte plate. Crystals become unstable and melt,
Aggregation and grain growth through reprecipitation, or a phase change to γ-lithium aluminate are likely to occur. As a result, the fine structure of the porous body changes, and electrolyte loss is likely to occur. The more preferable half-width of the (104) peak of α-LiAlO ₂ is 0.45 ° or less.

The holding material is 0.05 μm to 2.0 μm.
It is preferable that the powder has an average particle size of. When the average particle size of the holding material is less than 0.05 μm, the holding material in the porous body aggregates during the operation of the fuel cell in the electrolyte plate including the porous body having the holding material, and the particles easily grow. Become. On the other hand, if the average particle diameter of the holding material exceeds 2.0 μm, the holding property of the molten carbonate in the porous body having the holding material may be deteriorated. A more preferable average particle diameter of the holding material is 0.2 μm to 0.6 μm, and a further preferable average particle diameter of the holding material is 0.3 to 0.5 μm.

The above-mentioned holding material is manufactured by the following method. (1) A lithium aluminate powder mainly composed of α-lithium aluminate powder having a specific surface area of 20 m ² / g or more is used.
A holding material is manufactured by growing grains in a molten carbonate at 00 ° C to 800 ° C and then removing the carbonate.

The lithium aluminate powder mainly composed of α-lithium aluminate preferably contains α-lithium aluminate in an amount of 80% by weight or more, more preferably 90% by weight or more. The ratio of α-lithium aluminate that constitutes the lithium aluminate powder is 80
If it is less than wt%, it becomes difficult to obtain a holding material having a small amount of different phase lithium aluminate other than α-lithium aluminate.

When the specific surface area of the lithium aluminate powder is less than 20 m ² / g, the contact area with the molten carbonate becomes small, and it becomes difficult to perform good grain growth. The more preferable specific surface area of the lithium aluminate powder is 30 m ² / g or more. If the specific surface area of the lithium aluminate powder is too large, the volume (bulk) becomes large, and the production efficiency decreases, so the upper limit is 60 m ² /
It is desirable to set to g.

Examples of the carbonates include Li / K eutectic carbonates, Li / Na eutectic carbonates, Li / K / Na ternary eutectic carbonates, and mixed carbonates deviating from the eutectic salt composition. Salt or the like can be used.

The amount of the carbonate in the mixture of the α-lithium aluminate powder and the carbonate is preferably 5 to 70% by weight. When the amount of the carbonate in the mixture is less than 5% by weight, it becomes difficult to perform good grain growth. On the other hand, if the amount of the carbonate in the mixture exceeds 70% by weight, the productivity of the holding material may decrease. More preferably, the amount of the carbonate in the mixture is 10 to 50% by weight.

The temperature in the grain growth step is defined as follows.
The reason is as follows. If the temperature in the grain growth step is less than 700 ° C., it becomes difficult to rapidly grain grow the α-lithium aluminate powder having a high specific surface area. On the other hand, when the temperature in the grain growth step exceeds 800 ° C., α-lithium aluminate is converted to γ, and there is a possibility that grain growth may be excessive. More preferable temperature in the grain growth step is 730 ° C to 780 ° C.

The grain growth step is preferably performed in a carbon dioxide gas-containing atmosphere. By performing grain growth of the lithium aluminate powder in a carbon dioxide gas-containing atmosphere, it is possible to suppress gamma conversion of lithium aluminate in the grain growth process. The concentration of carbon dioxide in the atmosphere is preferably 1% or more, more preferably 10% or more.
The heat treatment in such an atmosphere containing carbon dioxide gas is 10 to
It is preferably carried out for 100 hours. In the grain growth step of the lithium aluminate powder, the higher the concentration of carbon dioxide in the atmosphere, the more stable the grain growth of α-lithium aluminate of the lithium aluminate powder.

After the grain growth step, the mixture of carbonate and lithium aluminate can be furnace cooled to room temperature and the carbonate can be removed with a solvent. As the solvent, for example, water or acetic acid can be used, but an acid or an organic acid aqueous solution which dissolves a carbonate but not lithium aluminate can also be used.

As described above, a lithium aluminate powder mainly composed of α-lithium aluminate having a high specific surface area is used as a starting material, and grains are grown in a molten carbonate to obtain high crystallinity and purity. It is possible to produce a holding material containing α-lithium aluminate in the form of single particles in a short time. A porous body is formed from the obtained holding material and the above-mentioned reinforcing material, and an electrolyte plate is prepared by impregnating the porous body with an electrolyte containing an alkali carbonate, and incorporating this into a molten carbonate fuel cell. As a result, the aggregation and particle growth of the holding material particles in the electrolyte plate can be suppressed, and the electrolyte loss can be reduced.

(2) A mixture of aluminum hydroxide powder having a specific surface area of 100 m ² / g or more and a carbonate containing lithium carbonate is heat-treated to produce lithium aluminate. Subsequently, the lithium aluminate is grain-grown in a molten carbonate, and then the carbonate is removed to produce a holding material.

By setting the specific surface area of the aluminum hydroxide powder to 100 m ² / g or more, the time required for lithiation can be shortened and the reaction can be made uniform.
The heat treatment of the mixture of the aluminum hydroxide powder and the carbonate is performed in an atmosphere containing 1 to 100% carbon dioxide gas.
It is desirable to carry out at 0 ° C to 700 ° C for 10 to 100 hours. 55 in an atmosphere containing at least 1% carbon dioxide
By heat treatment at 0 ° C. to 700 ° C., a highly pure α-lithium aluminate powder having a small amount of γ phase can be obtained. More preferable heat treatment temperature is 580 to 620 ° C.
Is.

As the carbonate containing lithium carbonate,
Li ₂ CO ₃ alone, or lithium carbonate and Li / K eutectic carbonate, Li / Na eutectic carbonate or Li / K / Na
A ternary eutectic carbonate or a mixture with a mixed carbonate deviating from the eutectic salt composition can be used.

The mixing molar ratio of the aluminum hydroxide powder and lithium carbonate (aluminum hydroxide: lithium carbonate) is preferably 1: 1 to 1: 3. The amount of the carbonate in the obtained mixture of the lithium aluminate powder mainly containing α-lithium aluminate and the carbonate is 5 to 70 for the same reason as described in the method (1). It is preferably set to the weight percent.

The temperature in the grain growth step is 700 ° C. to 80 ° C.
The reason for defining 0 ° C. is for the same reason as described in the method (1) above. The grain growth step is preferably performed in a carbon dioxide gas-containing atmosphere for the same reason as described in the method (1). The concentration of carbon dioxide in the atmosphere is preferably 1% or more, more preferably 10% or more.

After the grain growth step, the mixture of carbonate and lithium aluminate is furnace-cooled to room temperature, and the carbonate is removed with the same solvent as described in the above method (1). it can.

It should be noted that, even when alumina powder is used in place of the aluminum hydroxide powder in the production of the holding material, it is possible to produce a holding material having similar characteristics.

Reinforcing Material (b) This reinforcing material has a function of preventing cracks from being generated in the electrolyte plate due to the thermal cycle when starting and stopping the cell. Such a reinforcing material comprises at least one selected from lithium aluminate, alumina and stabilized zirconia, and particularly particles (b-1) and short fibers (b-2) made of the specific materials listed below. , Long fiber (b
-3) is preferred. However, the reinforcing material of the short fibers or the long fibers is allowed to consist of lithium diconate alone or a mixture of this lithium diconate and at least one selected from lithium aluminate, alumina and zirconia.

Particulate Reinforcing Material (b-1) The reinforcing material particles are made of at least one selected from α-lithium aluminate, γ-lithium aluminate, alumina and stabilized zirconia, and have an average particle size of 5 to 50 μm. Have a diameter. Such reinforcing material particles are unlikely to aggregate / aggregate with the holding material α-lithium aluminate, and can improve the stability of the fine structure of the electrolyte plate during operation. In particular, at least one selected from α-lithium aluminate, alumina and stabilized zirconia.
Particles made of seeds are preferable because they are more difficult to aggregate / aggregate with α-lithium aluminate as a holding material.

Short fibrous reinforcing material (b-2) The short fibrous reinforcing materials are β-lithium aluminate and γ.
-At least one selected from lithium aluminate, having an average diameter of 0.5 to 5 m and an average length of 50 m or less. Such a short fibrous reinforcing material has a smaller difference in radius of curvature from the holding material, α-lithium aluminate, as compared with the particulate reinforcing material, and thus it is difficult for the reinforcing material to absorb and coalesce the holding material. The stability of the fine structure of the electrolyte plate can be increased.

That is, during operation of the fuel cell, the reinforcing material and the holding material are repeatedly dissolved and re-deposited in the electrolytic solution. When the difference in radius of curvature between the reinforcing material and the holding material is large, a difference occurs in the dissolution rate of the reinforcing material and the holding material in the electrolytic solution during operation of the fuel cell. That is, the holding material dissolves in the electrolytic solution earlier than the reinforcing material. The holding material and the reinforcing material dissolved around the reinforcing material existing in the solid state in the electrolytic solution re-precipitates on the reinforcing material in the solid state, and as a result, the supporting material is dissolved and the reinforcing material is Grain grows. Therefore, the holding material is absorbed and united with the reinforcing material to form fine holes in the electrolyte plate, which causes electrolyte loss.

The short fibrous reinforcing material having the above-mentioned average diameter can reduce the difference in the radius of curvature from the holding material, so that the difference in the dissolution rate of the holding material and the reinforcing material in the electrolyte during operation of the fuel cell is small. it can. Therefore, in the reprecipitation process of the dissolved holding material and reinforcing material, the holding material and the reinforcing material are individually reprecipitated. As a result, since the holding material and the reinforcing material can suppress mutual dissolution and absorption coalescence, the stability of the fine structure of the electrolyte plate during operation can be enhanced.

Long fibrous reinforcing material (b-3) The long fibrous reinforcing material comprises at least one selected from alumina, lithium aluminate and zirconia,
It has an average diameter of 1 to 15 μm and an average length of 0.1 to 3 mm. Such a long fibrous reinforcing material is cracked in the electrolyte plate due to a difference in coefficient of thermal expansion between the anode and the edge seal plate, which are in close contact with the electrolyte plate when the battery is started, as compared with a particulate reinforcing material. Has the effect of effectively preventing the occurrence of

Further, by using the reinforcing materials of the above (b-1) to (b-3) in combination, the stability over time is excellent, and the initial cracks at the time of start-up and the occurrence of cracks at the time of thermal cycle are effective. It is possible to obtain a protected electrolyte plate.

Electrolyte (c) As this electrolyte, for example, lithium carbonate (Li ₂ CO)
₃ ), potassium carbonate (K ₂ CO ₃ ), a mixture of sodium carbonate (Na ₂ CO ₃ ), or Li ₂ CO ₃ and K
Examples thereof include a mixture of ₂ CO _3, a mixture of Li ₂ CO ₃ and Na ₂ CO _3, a mixture of Li ₂ CO ₃ , K ₂ CO ₃ and Na ₂ CO ₃ . The electrolyte is allowed to have a composition in which an alkaline earth metal carbonate is further added to the alkali carbonate or the mixed alkali carbonate.

The electrolyte plate described above is manufactured, for example, by the following method. (1) First, the holding particles, the reinforcing particles and the organic binder are mixed in the presence of an organic solvent. Examples of the organic binder used here include polyvinyl butyral, dibutyl phthalate, and acrylic resin. Examples of the organic solvent include toluene, xylene, methyl ethyl ketone, and the like. Subsequently, a porous sheet having a predetermined porosity is formed by degreasing the mixture after forming a green sheet by a usual sheet forming method (for example, a doctor blade method, a calendar roll method, a slip casting method, a cold extrusion method, etc.). Create the body. On the other hand, an electrolyte composed of a mixed alkali carbonate is seal-molded by the same method as that for the porous material to prepare a sheet-like material. Then, the sheet-shaped material is overlaid on the porous body, and the sheet-shaped material is melted to impregnate the porous body to manufacture an electrolyte plate.

(2) The electrolyte plate prepared by the method of (1) above is placed between an anode and a non-impregnated cathode which have been previously impregnated with an electrolyte composed of mixed alkali carbonate, and the unit cell shown in FIG. After stacking a plurality of unit cells with a separator sandwiched therebetween to form a stack power generation element, a manifold is attached to four side surfaces of the power generation element to assemble a fuel cell. Then, the temperature is raised to the operating temperature, and the molten mixed alkali carbonate in the anode is diffused and filled in the pores of the electrolyte plate to manufacture the electrolyte plate.

[0057]

The preferred embodiments of the present invention will be described in detail below. Example 1 A commercially available lithium aluminate powder having a specific surface area of 40 m ² / g and an amount of α-lithium aluminate of 98% by weight, and a eutectic carbonate (Li ₂ CO ₃ / K ₂ CO ₃ -62 /
38 mol%) were mixed in a weight ratio of 1: 1. This mixture was heat-treated in a carbon dioxide atmosphere at 750 ° C. for 50 hours.
The mixture after the heat treatment was cooled to room temperature and the carbonate was removed with water to obtain a powder (holding material).

It was confirmed by powder X-ray diffraction that the amount of α-lithium aluminate in the obtained powder was 95% by weight. When the average particle size of this powder was determined by image analysis, it was about 0.4 μm. In addition, α-Li of the powder
The full width at half maximum of the powder X-ray diffraction peak of the (104) plane of AlO ₂ was measured and found to be 0.36 °.

The powder X-ray diffraction pattern of α-lithium aluminate before treatment is shown in FIG. 4, and the powder X-ray diffraction diagram of α-lithium aluminate separated from the obtained powder is shown in FIG.
, Respectively. As is clear from these FIGS. 4 and 5, the powdered α-lithium aluminate has α-LiAl compared to the untreated α-lithium aluminate.
It can be seen that the full width at half maximum of the powder X-ray diffraction peak on the (104) plane of O ₂ is significantly narrowed.

Example 2 α-with a specific surface area of 23 m ² / g
Lithium aluminate powder and a eutectic carbonate similar to Example 1 were mixed in acetone in a 1: 1 weight ratio. After removing the acetone, the mixture was treated with carbon dioxide in an atmosphere of 75
Heat treatment was performed at 0 ° C. for 50 hours. The mixture after the heat treatment was cooled to room temperature and the carbonate was removed with water to obtain a powder (holding material).

The obtained powder is 100% by powder X-ray diffraction.
% Α-lithium aluminate was confirmed. When the average particle size of this powder was determined by image analysis, it was about 0.6 μm. In addition, α-Li of the powder
The full width at half maximum of the powder X-ray diffraction peak on the (104) plane of AlO ₂ was 0.48 °.

Example 3 α-with a specific surface area of 33 m ² / g
Lithium aluminate powder and the eutectic carbonate as in Example 1 were mixed in acetone in a weight ratio of 1: 1. After removing the acetone, the mixture was heated to a carbon dioxide gas atmosphere at 750 ° C.
And heat treated for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

The obtained powder is 100% by powder X-ray diffraction.
% Α-lithium aluminate was confirmed. When the average particle size of this powder was determined by image analysis, it was about 0.4 μm. In addition, α-Li of the powder
The full width at half maximum of the powder X-ray diffraction peak on the (104) plane of AlO ₂ was measured and found to be 0.39 °.

Example 4 α-with a specific surface area of 40 m ² / g
Lithium aluminate powder and the eutectic carbonate as in Example 1 were mixed in acetone in a weight ratio of 1: 1. After removing the acetone, the mixture was heated to 750 ° C. in a carbon dioxide atmosphere.
And heat treated for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

The powder obtained was analyzed by powder X-ray diffraction to be 100
% Α-lithium aluminate was confirmed. When the average particle size of this powder was determined by image analysis, it was about 0.4 μm. In addition, α-Li of the powder
The full width at half maximum of the powder X-ray diffraction peak of the (104) plane of AlO ₂ was measured and found to be 0.36 °.

Comparative Example 1 Commercially available specific surface area 17 m ² / g
Α-Lithium aluminate powder of Example 1 and eutectic carbonate similar to Example 1 were mixed in acetone at a weight ratio of 1: 1. After removing the acetone, the mixture was stirred under a carbon dioxide gas atmosphere for 7 hours.
Heat treatment was performed at 50 ° C. for 50 hours. After the heat-treated mixture is cooled to room temperature, the carbonate is removed with water to form a powder (holding material)
Got

From the powder X-ray diffraction, it was confirmed that the content of the α-phase lithium aluminate in the obtained powder was 3% by weight. (Comparative Example 2) A γ-lithium aluminate powder having a specific surface area of 20 m ² / g and an α-lithium aluminate content of 15% by weight and a eutectic carbonate similar to that of Example 1 were mixed with acetone in a weight ratio of 1: 1. Mixed in. After removing the acetone, the mixture was heat-treated in a carbon dioxide gas atmosphere at 750 ° C. for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

The powder thus obtained was confirmed by powder X-ray diffraction to have an α-lithium aluminate content of 20% by weight. (Comparative Example 3) A γ-lithium aluminate powder having a specific surface area of 20 m ² / g and a eutectic carbonate similar to that of Example 1 were mixed in acetone at a weight ratio of 1: 1. After removing the acetone, the mixture was heat-treated in a carbon dioxide gas atmosphere at 750 ° C. for 50 hours. After cooling the mixture after heat treatment to room temperature,
The carbonate was removed with water to obtain a powder (holding material).

From the powder X-ray diffraction, it was confirmed that the obtained powder had an α-phase lithium aluminate content of 0 and consisted of only the γ-phase. The holding materials obtained in Examples 1 to 4 and Comparative Examples 1 to 3 and γ-having an average particle diameter of 15 μm.
A reinforcing material composed of LiAlO ₂ particles was put in an alumina pot at a volume ratio of 70:30, and wet mixed with toluene, polyvinyl butyral and dibutyl phthalate for 20 hours to prepare 7 kinds of slurries, respectively. Next, spread each of these slurries on a carrier sheet,
A matrix green sheet having a thickness of 0.5 mm was prepared.
Subsequently, each of the matrix green sheets was degreased in the atmosphere to produce a porous body.

Further, mixed alkali carbonate (Li ₂ CO ₃ : 62 mol%, K ₂ CO ₃ : 38 mo as an electrolyte)
1%) was used to prepare a sheet-like material by the same method as that for the porous body. The sheet-like material is placed on each of the porous bodies and heated to 550 ° C. to bring the sheet-like material into a molten state, thereby impregnating each of the porous bodies with the mixed alkali carbonate. Seven types of electrolyte plates having a thickness of 0.5 mm were produced.

2 and 3 described above using the obtained electrolyte plates, the anode and cathode made of nickel base alloy, the separator made of stainless steel, the edge seal plate, the perforated plate, and the corrugated plate, respectively. The molten carbonate fuel cell shown in was assembled.

Under pressure at 5 atm for each fuel cell, a mixed gas of 80% by volume of H ₂ and 20% by volume of CO ₂ as a fuel gas was humidified and supplied at a partial pressure of water vapor of 1 atm to the anode, and a cathode was supplied. 70% by volume of air as an oxidant gas and 30% by volume of CO ₂ mixed gas are supplied to 700 ° C.
A power generation test was performed for 2000 hours under a load condition of 150 mA · cm ² . The operating potential drop of each fuel cell in such a power generation test was measured. The results are shown in Table 1 below. In addition, in Table 1 below, (104) of α-LiAlO ₂ of the holding materials of Examples 1 to 4 and Comparative Examples 1 to 3 was used.
The full width at half maximum of the powder X-ray diffraction peak on the surface is also shown.

[0073]

[Table 1]

As is clear from Table 1 above, α-LiAl
Mainly composed of α-lithium aluminate having a half-value width of the powder X-ray diffraction peak on the (104) plane of O ₂ of 0.60 ° or less.
It is understood that the fuel cells using the holding material (Examples 1 to 4) of 5 to 100% by weight) have an extremely low operating voltage drop of 130 mV or less after 2000 hours of pressurization operation and can maintain good cell performance. In particular, it can be seen that the fuel cells using the holding material (Examples 1, 3, and 4) having a half-width of 0.45 ° or less have an operating potential drop of 93 mV or less and have better cell performance.

On the other hand, in the fuel cells using the holding materials (Comparative Examples 1 to 3) having a small content of α-lithium aluminate, the operating potential drop after the pressurization operation for 2000 hours was 253 to.
It can be seen that it is extremely high at 392 mV.

(Examples 5 to 12, Comparative Examples 4 to 6) 40 m
² / g of α-lithium aluminate powder and eutectic carbonate as in Example 1 were mixed in acetone in a weight ratio of 1: 1. After removing the acetone, the mixture was heat-treated in the atmosphere, temperature and time shown in Table 2 below. After each heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain 11 kinds of powder (holding material).

Content of α-lithium aluminate in each powder obtained, powder X of α-LiAlO ₂ (104) plane
The full width at half maximum of the line diffraction peak and the average particle size were measured.
The full width at half maximum of the (104) peak of α-LiAlO ₂ was determined only for the powder mainly containing the α phase. The results are also shown in Table 2 below.

Further, the obtained Examples 5 to 12 and Comparative Example 4 were obtained.
Electrolyte plates were prepared in the same manner as in Example 1 using the holding materials Nos. 6 to 6, and the molten carbonate fuel cells shown in FIGS. 2 and 3 were assembled using these electrolyte plates. For these fuel cells, 150 mA / 700 ° C. as in Example 1.
A power generation test was performed for 2000 hours under a load condition of cm ² .
The operating potential drop of each fuel cell in such a power generation test was measured. The results are also shown in Table 2 below. The fuel cells using the holding materials of Comparative Examples 5 and 6 were 150 mA /
The load current of cm ² could not be taken out. For this reason, the values of the operating potential drop are not shown in Table 2 below.

[0079]

[Table 2]

As is clear from Table 2, the heat treatment in the grain growth step of the α-lithium aluminate raw material powder is 700 to
Examples 5-1 obtained by carrying out at a temperature of 800 ° C
In the powder (holding material) of No. 2, the half-value width of the powder X-ray diffraction peak of the (104) plane of α-LiAlO ₂ is 0.60.
An α-lithium aluminate powder having a temperature of ° or less was obtained. In particular, among Examples 6, 7, 11, and 12 which were heat-treated in an atmosphere of carbon dioxide gas concentration of 10% or more and at 730 to 780 ° C., those having sufficient heat treatment for 50 hours had a half width of 0.45. An ideal powder consisting of 100% pure α-lithium aluminate was obtained below °.

On the other hand, in Comparative Example 4 which was heat-treated at a temperature lower than 700 ° C., the full width at half maximum was large and the crystallinity was poor. Further, the powders of Comparative Examples 5 and 6 obtained by treating at a heat treatment temperature higher than 800 ° C. each had a low α phase content.

As is clear from Table 2, α-LiA
A fuel cell using a holding material (Examples 5 to 12) made of α-lithium aluminate having a powder X-ray diffraction peak on the (104) plane of 10 _{2 having} a half width of 0.60 ° or less was 2000.
It can be seen that the operating potential drop after the time pressurization operation is extremely low at 130 mV or less, and good battery performance can be maintained.

In contrast, α-LiAlO ₂ (10
The fuel cell using the holding material (Comparative Example 4) in which the full width at half maximum of the powder X-ray diffraction peak on the surface 4) exceeded 0.60 ° was 2000.
It can be seen that the operating potential drop after the time-pressurized operation is 272 mV, which is extremely high.

Example 13 First, 100 m ² / g of high-purity alumina powder and eutectic carbonate (Li ₂ CO ₃ / K ₂ C) were used.
O ₃ = 62: 38 mol%) and lithium carbonate were wet-mixed in acetone at a weight ratio of 2: 5: 3 (molar ratio 2: 5: 4). Subsequently, acetone was removed, and the mixture was heat-treated at 600 ° C. for 50 hours in a carbon dioxide atmosphere,
Further, it was heat-treated at 700 ° C. for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

Example 14 First, 100 m ² / g of high-purity alumina powder, the same eutectic carbonate as in Example 13 and lithium carbonate were wet mixed in acetone at a weight ratio of 2: 5: 3. Subsequently, acetone was removed, and this mixture was heat-treated at 600 ° C. for 50 hours in a carbon dioxide gas atmosphere, and then further heat-treated at 750 ° C. for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

(Example 15) First, 100 m ² / g of high-purity alumina powder, the same eutectic carbonate as in Example 13 and lithium carbonate were wet mixed in acetone at a weight ratio of 2: 5: 3. Subsequently, acetone was removed, and this mixture was heat-treated in a carbon dioxide gas atmosphere at 600 ° C. for 50 hours, and then at 800 ° C. for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

Comparative Example 7 First, 80 m ² / g of high-purity alumina powder, the same eutectic carbonate as in Example 13 and lithium carbonate were wet mixed in acetone at a weight ratio of 2: 5: 3. Subsequently, acetone was removed, and the mixture was heat-treated in a carbon dioxide atmosphere at 600 ° C. for 50 hours, and then further heated to 70
Heat treatment was performed at 0 ° C. for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

Comparative Example 8 First, 100 m ² / g of high-purity alumina powder, the same eutectic carbonate as in Example 13 and lithium carbonate were wet mixed in acetone at a weight ratio of 2: 5: 3. Subsequently, the acetone was removed, and the mixture was heat-treated at 600 ° C. for 50 hours in a carbon dioxide gas atmosphere, and then, further 8
Heat treatment was performed at 50 ° C. for 50 hours. After the heat-treated mixture is cooled to room temperature, the carbonate is removed with water to form a powder (holding material)
Got

(Comparative Examples 9 and 10) First, 100 m ² / g
The high-purity alumina powder of Example 1, the same eutectic carbonate as in Example 13, and lithium carbonate were wet mixed in acetone at a weight ratio of 2: 5: 3. Subsequently, acetone was removed, and this mixture was heat-treated at a temperature shown in Table 3 below for 50 hours in a carbon dioxide atmosphere. After each heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain two kinds of powder (holding material).

Examples 13 to 15 and Comparative Examples 7 to 10
The content of α-lithium aluminate of the powder obtained in
The full width at half maximum of the powder X-ray diffraction peak and the average particle size of the (104) plane of α-LiAlO ₂ were measured. The results are also shown in Table 3 below. In addition, α-LiAlO ₂ (10
4) The full width at half maximum of the peak was obtained by targeting only the powder mainly containing the α phase.

Further, an electrolyte plate was prepared in the same manner as in Example 1 using the obtained holding materials of Examples 13 to 15 and Comparative Examples 7 to 10, and these electrolyte plates were used for the above-mentioned FIG. 2 and FIG. The molten carbonate fuel cell shown in was assembled. For these fuel cells, 150 m at 700 ° C. as in Example 1.
A power generation test was performed for 2000 hours under a load condition of A / cm ² . The operating potential drop of each fuel cell in such a power generation test was measured. The results are also shown in Table 3 below.

[0092]

[Table 3]

As is clear from Table 3 above, the specific surface area is 10
Alumina raw material powder of 0 m ² / g or more is used at 600 ° C and 70
In Examples 13 to 15 which were heat-treated in two stages of 0 to 800 ° C, α-Li which showed good performance in the pressurizing operation test.
An α-lithium aluminate powder having a full width at half maximum of the powder X-ray diffraction peak on the (104) plane of AlO ₂ of 0.60 ° or less was obtained.

On the other hand, the powder of Comparative Example 7 obtained by using the alumina raw material powder having a specific surface area of less than 100 m ² / g had a large full width at half maximum and was inferior in crystallinity. Further, the powder of Comparative Example 8 obtained by heat treatment at a temperature exceeding 800 ° C. has a reduced α phase content. Further, the powders of Comparative Examples 9 and 10 obtained by the heat treatment in only one step had a large half width and poor crystallinity.

As is clear from Table 3, α-LiA
The fuel cell using the holding material (Examples 13 to 15) made of α-lithium aluminate having a powder X-ray diffraction peak on the (104) plane of 10 _{2 having} a half width of 0.60 ° or less was 200.
It can be seen that the operating potential drop after the 0-hour pressurization operation is extremely low at 130 mV or less, and good battery performance can be maintained.
On the other hand, the content of the α-lithium aluminate is low, or the powder X on the (104) surface of α-LiAlO ₂
It can be seen that the fuel cells using the holding material (Comparative Examples 7 to 10) having a half-width of the line diffraction peak of more than 0.60 ° have an extremely high operating potential drop of 253 mV or more after 2000 hours of pressurization operation.

Example 16 First, 100 m ² / g of high-purity aluminum hydroxide powder and eutectic carbonate (Li ₂ CO ₃
/ K ₂ CO ₃ = 62: 38 mol%) and lithium carbonate in acetone at a weight ratio of 2: 5: 3 (molar ratio 2: 2).
Wet mixing was performed at 5: 4). Subsequently, acetone was removed, and this mixture was heat-treated at 600 ° C. for 50 hours in a carbon dioxide gas atmosphere, and then further heat-treated at 700 ° C. for 50 hours. After the heat-treated mixture was cooled to room temperature, the carbonate was removed with water to obtain a powder (holding material).

The obtained powder is 100% by powder X-ray diffraction.
% Α-lithium aluminate was confirmed. When the average particle size of this powder was determined by image analysis, it was about 0.3 μm. In addition, α-Li of the powder
The full width at half maximum of the powder X-ray diffraction peak on the (104) plane of AlO ₂ was measured and found to be 0.41 °.

Example 1 using the obtained powder (holding material)
An electrolyte plate was produced by the same procedure as in. With this electrolyte plate,
The anode and cathode made of nickel base alloy, the separator made of stainless steel, the edge seal plate, the perforated plate, and the corrugated plate, respectively, are used for the above-mentioned FIG.
And the molten carbonate fuel cell shown in FIG. 3 was assembled.
For this fuel cell, the same pressurization as in Example 1 and the supply of fuel gas and oxidant gas were performed, and the temperature was increased to 150 ° C. at 150 ° C.
A power generation test was performed for 2000 hours under a load condition of mA · cm ² . The operating potential drop of the fuel cell in such a power generation test was measured. As a result, the operating potential drop was 65 mV, and good battery performance was maintained.

(Examples 17 to 24) The powder (holding material) obtained in Example 4 and the reinforcing material having the material and shape shown in Table 4 below were put in an alumina pot at a volume ratio of 70:30. , Toluene, polyvinyl butyral, and dibutyl phthalate were wet-mixed for 20 hours to prepare 8 types of slurries, respectively. Subsequently, each of these slurries was spread on a carrier sheet to form a matrix green sheet having a thickness of 0.5 mm. Subsequently, each of the matrix green sheets was degreased in the atmosphere to produce a porous body.

Further, mixed alkali carbonate (Li ₂ CO ₃ : 62 mol%, K ₂ CO ₃ : 38 mo as an electrolyte)
1%) was used to prepare a sheet-like material by the same method as that for the porous body. The sheet-like material is placed on each of the porous bodies and heated to 550 ° C. to bring the sheet-like material into a molten state, thereby impregnating each of the porous bodies with the mixed alkali carbonate. Eight types of electrolyte plates having a thickness of 0.5 mm were produced.

A molten carbonate fuel cell shown in FIGS. 2 and 3 was assembled in the same manner as in Example 1 by using the obtained electrolyte plates. For these fuel cells, as in Example 1, 7
A power generation test was carried out for 2000 hours at 00 ° C. under a load condition of 150 mA / cm ² . The operating potential drop of each fuel cell in such a power generation test was measured. The results are shown in Table 4 below.
Also described in. In addition, in Table 4 below, electrolyte plates were prepared using the holding materials of Examples 1 to 4 and Comparative Examples 1 to 3 and the reinforcing material made of γ-LiAlO ₂ powder having an average particle size of 15 μm. The operating potential drop of the molten carbonate fuel cell shown in FIGS. 2 and 3 assembled in the same manner as in Example 1 using these electrolyte plates is also shown.

[0102]

[Table 4]

As is clear from Table 4, Examples 17 to
In the fuel cell of Example 24, the same operating materials as those of Examples 17 to 24 are used as the holding material, and the operating voltage drop can be further suppressed as compared with the fuel cell of Example 4 using the γ-LiAlO ₂ particles as the reinforcing material. I understand. In particular, it can be seen that the fuel cell of Example 24 using the composite material of α-lithium aluminate particles and long fibers as the reinforcing material can further suppress the operating voltage drop.

[0104]

As described above, according to the present invention, it is possible to suppress the change in the microstructure of the electrolyte plate, to suppress the increase in the resistance of the electrolyte plate due to the electrolyte loss, and to operate for a long time even under a pressurized condition. A molten carbonate fuel cell can be provided.
Further, according to the present invention, the electrolyte holding material most suitable for the fuel cell can be stably manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the basic structure of a molten carbonate fuel cell.

FIG. 2 is a perspective view showing a general configuration of a molten carbonate fuel cell according to the present invention.

3 is an enlarged perspective view of a main part of the fuel cell of FIG.

FIG. 4 is a powder X-ray diffraction diagram of α-lithium aluminate before treatment in Example 1.

FIG. 5: α separated from the powder obtained according to Example 1.
-Powder X-ray diffractogram of lithium aluminate.

[Explanation of symbols]

11 ... Anode, 12 ... Cathode 13 ... Electrolyte plate, 14 ... Separator, 19 ... Manihold, 21 ... Fuel gas, 24 ... Oxidizer gas.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuaki Nakagawa 1 Komukai Toshiba Town, Komukai-shi, Kawasaki-shi, Kanagawa, Toshiba Research and Development Center Co., Ltd. (56) Reference JP-A-8-55628 (JP, A) JP-A-2-243511 (JP, A) JP-A-6-267568 (JP, A) JP-A-7-220749 (JP, A) JP-A-8-250137 (JP, A) JP-A-6-150948 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 8/02

Claims (9)

(57) [Claims] 1. An electrolyte in which a porous body, which is sandwiched between a fuel electrode, an oxidizer electrode, and the fuel electrode and the oxidizer electrode, and which contains a holding material and a reinforcing material, is impregnated with an electrolyte containing an alkali carbonate. A plate, wherein the holding material is α-lithium having a specific surface area of 20 m ² / g or more.
Dissolves lithium aluminate, which is mainly aluminum
By growing grains in molten carbonate and removing the carbonate
90% by weight or more of the obtained α-lithium aluminate is contained.
A, and the alpha-LiAlO ₂ in the powder X-ray diffraction
(104) Lithium with a half-value width of 0.60 ° or less
A molten carbonate fuel cell , comprising an aluminate and the reinforcing material comprising at least one selected from lithium aluminate, alumina and stabilized zirconia. 2. The holding material is a powder having an average particle diameter of 0.05 to 2.0 μm.
The molten carbonate fuel cell described. 3. The holding material is α in powder X-ray diffraction.
Of -LiAlO ₂ (104) full width at half maximum of the peak is 0.45
The molten carbonate fuel cell according to claim 1, wherein the molten carbonate fuel cell has a temperature of not more than °. 4. The molten carbonate fuel cell according to claim 1, wherein the holding material is made of α-lithium aluminate. 5. An electrolyte in which a porous body, which is sandwiched between a fuel electrode, an oxidizer electrode, and the fuel electrode and the oxidizer electrode, and which contains a holding material and a reinforcing material, is impregnated with an electrolyte containing an alkali carbonate. A plate, wherein the holding material is α-lithium having a specific surface area of 20 m ² / g or more.
Dissolves lithium aluminate, which is mainly aluminum
By growing grains in molten carbonate and removing the carbonate
90% by weight or more of the obtained α-lithium aluminate is contained.
A, and the alpha-LiAlO ₂ in the powder X-ray diffraction
(104) Lithium with a half-value width of 0.60 ° or less
A molten carbonate fuel cell , comprising an aluminate and the reinforcing material comprising at least one fiber selected from lithium aluminate, alumina, stabilized zirconia, and lithium zirconate. 6. The molten carbonate fuel cell according to claim 5, wherein the reinforcing material is a short fiber having an average diameter of 0.5 to 5 μm and an average length of 50 μm or less. 7. The molten carbonate fuel cell according to claim 6 , wherein the reinforcing material is made of at least one selected from β-lithium aluminate and γ-lithium aluminate. 8. The reinforcing material has an average diameter of 1 to 15 μm,
The molten carbonate fuel cell according to claim 5, which is a long fiber having an average length of 0.1 to 3 mm. 9. The molten carbonate fuel cell according to claim 8 , wherein the reinforcing material is made of at least one selected from alumina, lithium aluminate and zirconia.